Messages in this thread | | | Date | Wed, 25 May 2005 13:40:56 -0700 | From | Mike Kravetz <> | Subject | Re: Avoiding external fragmentation with a placement policy Version 11 |
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On Sun, May 22, 2005 at 09:05:07PM +0100, Mel Gorman wrote: > /* > + * Calculate the size of the zone->usemap > + */ > +static unsigned long __init usemap_size(unsigned long zonesize) { > + unsigned long usemapsize; > + > + /* - Number of MAX_ORDER blocks in the zone */ > + usemapsize = (zonesize + (1 << (MAX_ORDER-1))) >> (MAX_ORDER-1); > + > + /* - BITS_PER_ALLOC_TYPE bits to record what type of block it is */ > + usemapsize = (usemapsize * BITS_PER_ALLOC_TYPE + (sizeof(unsigned long)*8)) / 8; > + > + return L1_CACHE_ALIGN(usemapsize); > +}
In the first calculation, I think you are trying to 'round up'. If this is the case, then I believe the calculation should be:
usemapsize = (zonesize + ((1 << (MAX_ORDER-1)) - 1) >> (MAX_ORDER-1);
I don't know if there is a similar issue in the second calculation. Arithmetic is not one of my strengths.
-- Mike - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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